Impact of CYP3A5 and MDR1(ABCB1) C3435T polymorphisms on the pharmacokinetics of tacrolimus in renal transplant recipients

Objective. The objective of this study was to assess the influence of CYP3A5 and MDR1 genetic polymorphisms on tacrolimus pharmacokinetics in Japanese renal transplant recipients. Method. The pharmacokinetic parameters of tacrolimus were calculated in steady-state on day 28 after transplantation. Polymerase chain reaction-restriction fragment length polymorphism and direct sequence methods were used for CyP3A5 and MDR1 polymorphisms, respectively. Results. The dose-adjusted area under the concentration-time curve (AUC(0-12)) was significantly lower among CYP3A5*1 carriers than those bearing CYP3A5 *3/*3. (0.570 +/- 0.105 vs 0.865 +/- 0.343 ng (.) h/mL per mg/kg, P = .00322). The daily tacrolimus dose per body weight was significantly higher in CYP3A5*1 carriers than those of Cyp3A5*3/*3 carriers (0.271 +/- 0.110 vs 0.150 +/- 0.056 mg/kg, P = .00016). In this study, a distinction was made between carriers of CYP3A5*1/*1 + *1/*3 and CYP3A5*3/*3 to investigate the influence of the MDR1 C3435T mutation on tacrolimus pharmacokinetics. The MDR1 C3435T polymorphisms did not affect any tacrolimus pharmacokinetic parameter in either group. Conclusions. Renal transplant recipients who were CYP3A5*1 carriers required a higher dose of tacrolimus than CYP3A5*3/*3, indicating a significantly lower dose-adjusted AUC(0-12) of tacrolimus. In contrast, MDR1 C3435T polymorphism was not an important factor in tacrolimus pharmacokinetics.